Bit for boring square and angular-shaped holes.



J` W. CALBWELL.

BIT POR. BORING SQUARE AND ANGLAR SHAPED HD2-'SS Urmonxou nur man 24, ma. ammwzv mm s, 1m.

1,066,708.. Patented July 19m gli'.

Willa 254124.144v41`,

' UNITED sTATEs PATENT ernten.

JOHN WILLIAM CALDWELL, OF TORONTO, ONTARIO, CANADA.

BIT FOR BORING SQUARE AND ANGULAR-SHAPED HOLES.

Speclcation of Letters latent.

Patented July 8, 1913.

Application tiled June 24, 1908, Serial No. 440,179. Renewed December 2, 1912. Serial No. 734,629.

To lll whom it may concern Beit known that I, JonN WILLIAM CannwELL, a subject ot the King of Great Britain, and residentl of the city of Toronto', in the l county of York. in the AProvince of Onbit formed in cross section with parallel straight faces of considerably greater width than halfthc diameter of the bit.

The objects of the. invention are to devise abit for cutting square or angular shaped holes quickly and perfectly and prevent choking and .to provide a tool for said purpose of cheap, simple and durable construction.

In the drawings Figure 1 is a side view of the bit proper showingr the broach mounted thereon and turned cornerwise. Fig. 2 is a side view of the bit proper showing the broaeh from another point of view. Fig. 3 is a side View ofthe bit proper and showA ing the broach in section and a cross section of the spiral broken away internict'liate of its length. Fig. 4 is an end view of the bit proper and the broach. Fig. 5 is a cross section on the line A B in Fig. 1. Fig. 6 is an end View of a bit for cuttingr a doretail hole. Fig. 7 is an end view of a bit vfor cutting a hexagonal hole. Fig. 8 is an end View of a bit for cutting an octagonal hole.

Like numerals of reference indicate corresponding parts in cach figure.

Referring to the drawings 1 is the rotary A member or bit proper formed of the spiral '2 having parallel straight faces 53 and lateral flanges 4 at the outer edges forming a pair of spiral channels of greater width than half the diameter ot the hole cut thereby. The bit 1 is tlared outwardly at the bottom end and the lower end of the spiral is sharpened between the flanges 4 to forni the horizontal cutters 5. The flanges t extend beyond the horizontal cutting edges 5 and are sharpened to forni side cutters.

6 is a lead screw haring adouble thread forming a continuation ofthe horizontal cutters 5. said threads being undercut on the inner surfaces of the thread presenting downwardlyv projecting cutting edges. said threads terminating in a pair of downwardly extending chisel points 7 extending beyond the tapered point of the central core 8. The top 9 of the bit is square to fit into the separable shank 10. l

11 is an angular Shaped broach of exactly the same diameter as the cutting end of the bit proper 1 having a centralY circular orifice 12 extending therethrough. The orifice 12 has a long bevel at the lower .end corresponding with the outward flare of the bit 1 *and terminates at each corner 13 in an extending chisel point or guillotine edge. The side cutters of the bit 1, in rotation extend flush with the outer flat faces of the broach 11 .so that it cuts a circular hole of exactlv the saine diameter as the breach. It will therefore be'secn that the broach has only to cut away the tilletsin said circular hole to forni the square or angular hole.

l-l is a loose washer encircling the bit above the breach 11.

l5 is a collar encircling the bit 1 and secured thereto by the set screw 16, said collar being adjusted to hold the washer 14 against the upper end of the breach 11 and to hold the tapered inner wall of said breach Closely to the flared portion of the bit 1. The shank 10 and bit 1 are rigidly secured to'- gether by a suitable pin after the breach 11 yand washer and holding collar are mounted thereon. The channels formed in the bit 1 are. in the reduced portion of said bit, considerably wider than half the diameter of the cutting end, so that there is sutticient' tillcts.

loo

.the rotating hit.

Three modifications of the sha of the hroaeh are shown in Figs. G, 7 an 8, but it mus-t he understood that many changes may he made in the form thereof so long as the stationary `guillotine edges for cutting away the fillets are associated with a rotating enttingr member.

'lhe' form of hit herein .shown and described is adapted for use in a hand brace, or it may he used with equal facility in wood working machines of. various kinds, and may also he used for burin;r mortises or other long shapes ot holes by modifying the shape ot the hroaeh and using two or .more rot-ati ing members.

'l`he present invention relates particularly to the adaptation of the auger bitl described in my eti-pending application 440,177 to a hit for boring .square and angular shaped holes.

I'litherto it. has not been possible to bore .square or angular shaped holes successfully on account ol the clogging and choking of In the present invention however, the spiral of the rotating member is, so .formed that there is ample clearance for the chips and a successfully operating hit is produced.

ll'hat I claim as my invention is 1. An auger bit, comprising, a. spiral body portion haringI` a cross sectional shape shovving' parallel .straight 'far-es .said straight faces presenting channels ot greater width than half the diameter of the hit., and a hollow hroaeh surroumlingr said hit` above the cutting end and having angularly arranged sides and chisel edgesI at the lower end thereof.

2. An auger bit, comprising, a spiral body portion having a cross sectional shape showing parallel straight than hall' the `iameter of the bit., said bit terminating in cutting edges to each side of the central lead screw and having side tlanges forming side cutters at the bottom end, and a hollow broach bit above the cutting end and having angularly arranged sides and chisel edges at the lower end thereof.

3. An auger bit, comprising, a spiral body portion having a cross sectional shape showing parallel straight faces, said .straight faces presentingr channels of greater width than half the diameter of the bit, the spiral of said bit increasing in diameter toward its lower end and forming a radual flare t0 said bit, said bit. having sige tlanges formingr side cutters at the bottom` end, and a hollow broaeh surroundinr said bit and having angularly arranged sides, saidsides having the inner wall flaring outwardly and forming chisel edges at the lower end thereof.v l

Sigi'ied at the city of Toronto in the county of York in the Province of Ontario,

in .the Dominion of Canada., this 116th day ot' June 1908. l

JOHN lVILLl'AM CALDWELL. \\'it uesses:

Il. DENNISON, iVm. C. MUIR.

faces, said straight faces presentino channels of greater width surrounding said 

